Dispensers of fluid products are known which are screwed on a container in a fluid product to be dispensed and which, therefore, also serve as closing stoppers for said containers.
Known dispensers comprise a dosing chamber with variable volume to aspirate and subsequently dispense a portion of the fluid product from the container.
In detail, when the volume of the dosing chamber is reduced, the overpressure thus determined expels the portion of fluid product contained towards the exterior, whilst when the volume of the dosing chamber is increased the vacuum thus created aspirates a successive portion of product from the container to the dosing chamber. Appropriate check valves regulate the flows just described.
The dosing chamber is obtained in a main body that can be stably associated to the container by means of a closing ring nut.
In a first embodiment, the dosing chamber is delimited by a translatable piston that defines a movable wall of the dosing chamber. The translation of the piston determines a decrease or an increase in the volume of the dosing chamber.
The piston is actuated, through an appropriate stem, by a dispensing head that is pressed by a user to reduce the volume of the dosing chamber and obtain the delivery of a portion of fluid product. In this case, the fluid product escapes from the dispensing head through an outlet conduit obtained in a single piece with the dispensing head itself.
A spring made of metallic material is positioned within the main body of the prior art dispenser to enable the dispensing head, and consequently the piston, to return to the initial position, thereby completing the step of aspirating the fluid product.
These prior art devices further comprise intake and delivery valves that regulate the flow of the fluid product respectively into and out of the dosing chamber.
In detail, during a step of aspirating the fluid product into dosing chamber, the intake valve opens to enable the fluid to enter the chamber, whilst the delivery valve remains closed to prevent the product from flowing back from the dispensing nozzle. During a step of dispensing the fluid product, vice versa, the intake valve closes and prevents the product from flowing back into the container, whilst the delivery valve opens to enable it to flow out of the dispensing spout.
In prior art devices, the intake valve usually comprises a ball located in a corresponding seat obtained in a lower portion of the dosing chamber; the delivery valve is obtained through the sliding of the piston on the stem that supports it, or in some cases, by means of a ball of the type just described.
This first type of device comprises locking means active on the dispensing head to prevent unwanted operation of the head itself and, hence, accidental spillage of fluid product. These locking means comprise a plurality of ribs obtained on the dispensing head which engage, in a locked configuration, in corresponding seats obtained on the main body. In an unlocked configuration, reached by relative rotation of the dispensing head with respect to the main body, the ribs disengage from the corresponding seats and allow the dispensing head to move.
Disadvantageously, this type of dispenser is frequently subjected to blocks determined by the sliding of the piston inside the dosing chamber. During its actuation, the piston is in contact with the lateral walls of the dosing chamber and product residues can limit or prevent the actuation of the piston with consequent block of the dispenser by seizing. An additional advantage of this kind of dispenser is that it is constituted by a relatively high number of components. This makes the productive process more complex and expensive.
Also, the presence of metallic components, e.g. the return valve and/or the ball, sets substantial limits both in terms of usage capability, since possible contact with the product can determine corrosion problems, and of the possibility to recycle the dispenser after use.
In a second embodiment, the dosing chamber is defined at least in part by a hemispheric cap made of elastic, deformable material, which can be operated directly by the user. More in detail, the dosing chamber is defined by at least one wall obtained in the main body and by the aforementioned cap.
In use, the user presses the cap to determine a decrease in volume and the consequent ejection of the fluid product contained. When the user releases the cap, it elastically returns to the initial configuration, increasing its volume and aspirating an additional portion of fluid product that will be dispensed later.
In this case, too, there are interception systems that regulate the inflow and outflow. In some embodiments, the intake valve comprises a ball housed in the corresponding seat and operating with the same principle illustrated above.
In alternative embodiments, the intake valve is obtained by shaping the cap itself, thereby avoiding the need for the presence of the metal ball.
This type of device can comprise blocking means comprising a rigid shell that is superposed, in a blocking configuration, to the deformable cap to prevent accidental compressions thereof Said shell, hinged to the main body, is lifted by the user to expose the cap in an unblocking configuration.
Disadvantageously, however, in this type of dispensers it is possible for the membrane to be lacerated, since it is directly operated by the user. Consequently, the product contained in the dosing chamber escapes and the dispenser becomes unusable.
Moreover, dispensers of this kind are not very practical and intuitive both with regards to its unblocking and operating procedures, also because of their limited distribution.